Apparatus for conveying and exposing a strip of radiant energy sensitive material

ABSTRACT

An apparatus for conveying and exposing a radiant energy sensitive strip of material, such as flexible printed circuit material, utilizes a plurality of carriages movable along closed tracks. Each carriage has a mask thereon against which the strip is pressed as the carriages are moved past a radiant energy source. Each mask is mounted free to move within predetermined limits relative to the carriage so that registration pins on each mask can be accurately aligned with registration holes punched in successive sections of the strip. The tracks along which wheels on the carriages roll include a plurality of circular outwardly facing and inwardly facing tracks located in parallel planes. Each carriage has spring biased arms with wheels engaging the inwardly facing tracks to retain the carriages on the tracks. In a second carriage and track arrangement, the inwardly facing tracks are eccentric with the outwardly facing tracks so that the spring biased arms urge the carriage toward the point when the inwardly facing tracks are closest to the outwardly facing tracks.

United States Patent Harris [451 July 18, 1972 [54] APPARATUS FOR CONVEYING AND EXPOSING A STRIP OF RADIANT ENERGY SENSITIVE MATERIAL [21] Appl.No.: 80,365

[52] [1.8. CI ..355/96, 355/108, 355/109 [5 l] Int. Cl. [58] Field of Search ..355/96, 78, 84, 80, SL102,

355/103, I09, 110, I04, I08, ill

[56] References Cited UNITED STATES PATENTS 7/l 898 6/ l 951 6/ l 954 Schwarz...

Miller Van Der Grinten ..355/l10 X Primary Examiner-Samuel S. Matthews Assistant Examiner-Richard L. Moses Artomey-W. M. Kain, R. P. Miller and W. L. Williamson ABSTRACT An apparatus for conveying and exposing a radiant energy sensitive strip of material, such as flexible printed circuit material, utilizes a plurality of carriages movable along closed tracks. Each carriage has a mask thereon against which the strip is pressed as the carriages are moved past a radiant energy source. Each mask is mounted free to move within predetermined limits relative to the carriage so that registration pins on each mask can be accurately aligned with registration holes punched in successive sections of the strip. The tracks along which wheels on the carriages roll include a plurality of circular outwardly facing and inwardly facing tracks located in parallel planes. Each carriage has spring biased arms with wheels engaging the inwardly facing tracks to retain the carriages on the tracks. in a second carriage and track ar rangement, the inwardly facing tracks are eccentric with the outwardly facing tracks so that the spring biased arms urge the carriage toward the point when the inwardly facing tracks are closest to the outwardly facing tracks.

l2 Claims, 16 Drawing Figures Patented July 18, 1972 8 Sheets-Shea t f Patented July 18, 1972 8 Sheets-Sheet 5 Patented July 18, 1972 8 Sheets-Sheet 4 Patented July 18, 1972 8 Sheets-Sheet 5 Patented July 18, 1972 8 Sheets-Sheet 6 Patented July 18, 1972 8 Sheets-Sheet 7 APPARATUS FOR CONVEYING AND EXPOSING A STRIP OF RADIANT ENERGY SENSITIVE MATERIAL RELATED APPLICATION Application Ser. No. 83,915 pending in 164 entitled Process Of Making Metal Circuits On Insulative Strip Material" filed on Oct. 26, 1970 by Messrs. D. E. Campbell and R. A. Harris and assigned to Western Electric Company, Incorporated, relates to a method for making printed circuit boards which may utilize the apparatus of this invention.

BACKGROUND OF THE. INVENTION 1. Field of the Invention This invention relates to an apparatus for conveying and handling strip material and particularly relates to an apparatus for exposing a radiant energy sensitive strip to actinic radiant energy through a mask or master. Such apparatus may be used in the manufacture of printed circuits.

Printed circuits for use in electronic equipment may be manufactured in one of many processes. One process utilizes a flexible insulative strip which has a metal, such as copper, coating or foil laminated thereon. The metal coating is covered with a radiant energy sensitive resist. The radiant energy sensitive resist is exposed to actinic radiant energy through a mask which allows the radiant energy to pass only to selected areas of the resist. The resist is then developed to leave a resist pattern on the selected areas and the metal coating not covered by resist is etched away to leave a metal circuit pattern.

Alternately, the radiant energy may be blocked from selected areas of the resist, and after developing, the selected areas of metal not covered by resist are plated with an etch re sistant metal or alloy, such as solder. All the resist is then removed and the nonplated metal is etched away leaving a circuit pattern.

Holes may be formed through the strip before the circuit patterns are formed, thereon so that component leads may be inserted or so that electrical paths may be formed through the holes to connect circuit patterns on opposite sides of the strip. These holes must be accurately aligned with the printed circuits.

2. Prior Art There are a number of prior art apparatus for conveying and handling strip material where the material is exposed to actinic light through a master or a mask. One such prior art apparatus advances a section of a strip into a printing station where the strip is stopped and the section of the strip is forced by use of a vacuum or air pressure difl'erential against a mask in registration with the mask and an actinic radiant energy source exposes the strip through the mask. This prior an apparatus is slow and requires a considerable amount of operator time.

Another prior art apparatus employs a transparent drum with the masks mounted on the periphery of the drum. With this apparatus the masks cannot be accurately aligned with holes in the strip since holes punched in successive sections of the strip often are not uniform in distance and alignment with adjacent sections.

SUMMARY OF THE INVENTION An object of the present invention is a new and improved apparatus for advancing a strip of material through a work station.

Another object of the invention is an apparatus for readily aligning a material holder, such as a mask, with a strip of material as it moves continuously through a work station.

A further object of the invention is an apparatus wherein masks are brought into accurate registration with a strip of radiant energy sensitive material as it moves continuously past an actinic radiant energy source.

In accordance with these and other objects, an embodiment of the invention includes a track running past a radiant energy source with a plurality of individual carriages having masks thereon movable along the track in registration with a strip of radiant energy sensitive material. The strip is exposed to radiant energy through the masks as the strip and individual carriages pass the radiant energy source.

An additional feature is that each of the masks are mounted on its carriage for limited movement relative thereto with registration pins in the mask for aligning the mask with regstration holes in the strip as the strip passes through a beam of actinic radiant energy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cut away portion of a metal clad insula tive strip used in the manufacture of printed circuits;

FIG. 2 illustrates a punch and die arrangement for producing a pattern of holes in successive sections of a strip;

FIG. 3 is a view of holes punched in successive sections of a strip by the apparatus shown in FIG. 2;

FIG. 4 illustrates an apparatus for applying a radiant energy sensitive material or covering to the surfaces of a strip;

FIG. 4A shows a cut away portion of a metal clad insulative strip with radiant energy sensitive material covering portions of the metal surfaces of the strip;

FIG. 5 illustrates an apparatus for conveying a strip through a work station, and particularly, for conveying a radiant energy sensitive strip through a beam of actinic radiant energy with a mask between the radiant energy source and the strip;

FIG. 6 is a pictorial drawing of some of the apparatus shown in FIG. 5 illustrating in more detail various features of the apparatus;

FIG. 7 is a pictorial drawing of a carriage which rolls on tracks of the apparatus shown in FIGS. 5 and 6;

FIG. 8 is a pictorial drawing of a mask which is mounted on the carriage shown in FIG. 7;

FIG. 9 is a top view of an alternate overlay which may be used in place of the overlay shown in FIG. 8;

FIG. 10 shows a cut away portion of a flexible belt used in the apparatus of FIGS. 5 and 6 for forcing the strip of material against the mask on the carriages and moving the carriages and strip past the radiant energy source;

FIG. IIv illustrates an arrangement of driving chains and clutches for operating the apparatus of FIGS. 5 and 6;

FIG. I2 shows a housing for a radiant energy source which may be utilized in the apparatus of FIGS. 5 and 6;

FIG. 13 shows a rocking guide roller which may be utilized to aid in guiding the strip in registration with pins on the masks of the apparatus of FIGS. 5 and 6;

FIG. 14 illustrates a roller press assembly for the apparatus shown in FIGS. 5 and 6 for pressing the resilient belt tightly against the strip of material; and

FIG. 15 illustrates a slack sensing mechanism for controlling the advancement of the strip of material through the forward and rear sections of the apparatus shown in FIGS. 5 and 6 to insure the material is properly fed to each of the sections.

DETAILED DESCRIPTION Referring to FIG. I there is shown a section of strip 20 which has an insulative film 2], such as flexible epoxy film, which is covered with a layer of metal 22 on the top thereof and a layer of metal 23 on the bottom thereof to form a laminate structure. The metal layers 22 and 23 may be copper foils which are bonded to the film 2] for use in the manufacture of printed circuits. Many varieties of such metal coated insulative strips are commercially available and may be purchased in rolls.

Refen'ing now to FIG. 2, the strip 20 is advanced from a supply roll 26 between a punch 27 and a die 28 by an indexing wheel 29. The punch 27 is closed with the die 28 to produce a pattern of holes in succeeding sections 31a, 31b, and 31c of the strip as shown in FIG. 3. Suitable facilities (not shown) are provided for automatically advancing the indexing wheel through a predetermined angle to successively place the sections of the strip 20 between the punch 27 and die 28. The

punched strip 20 is then wound on the take-up roll 30. As shown in FIG. 3, the punch 27 forms a plurality of holes 32- 32 along the edges of each section of the strip 20 for registration purposes. A plurality of holes 33-33 are formed in each section to accommodate the leads of components or to be used as a path for a through-hole connection between circuit patterns on the upper and lower surfaces of the strip 20. The apparatus for indexing and forming the holes 32-32 and 33- 33 in the strip cannot accurately form the holes in each section in alignment with the holes in adjacent sections. Also, the distance between adjoining sections varies considerably. Thus, the distance between sections 31a and 31b is different from the distance between 31b and 31c. Also, the holes 32 in the section 31b are not aligned with the holes 32 formed in the adjoining sections 310 and 31c.

After punching holes through the strip 20, the metal surface areas where circuit patterns are to be made on the strip 20 are covered with a radiant energy sensitive resist material. The resist material may be a silver halide emulsion which is sprayed, dipped, or otherwise coated on the surfaces of the strip 20 or the resist material may be a photopolynierizable monomer. In FIG. 4 there is shown an apparatus for applying one type of photopolymerizable monomer material to the upper and lower surfaces of the strip 20. The strip 20 is fed from a supply roll 35 between a pair of pressing rollers 36 and 37 to a take-up roll 44. Strips of photopolymerizable monomer are fed from rolls 38 and 39 and bonded to the respective upper and lower surface of the strip 20. The photopolymerizable strips from the rolls 38 and 39 have respective transparent support films 40a and 41a upon which layers 40b and 41b of photopolymerizable monomer emulsion are deposited. Cover films 42 and 43 are removed and wound on rolls 44 and 45 prior to the rollers 36 and 37 pressing the respective layers 40b and 41b on support films 40a and 410 against the metal surfaces 22 and 23. A sandwich structure or strip 200, shown in FIG. 4A, is produced, wherein the layers 40!; and 41b of photopolymerizable monomer emulsion cover and firmly adhere to the metal surface areas where printed circuit patterns are to be made. If the metal surfaces have been properly cleaned by conventional techniques, such as scrubbing with a pumice, the support films 404: and 41a may be removed, either before or afler exposure of the strip 200 to actinic radiant energy, and the layers 40b and 41b remain firmly adhering to the respective metal layers 22 and 23. Suitable rolls of strips of photopolymerizable material are sold under the trademark Riston by DuPont DeNemours & Company of Delaware and under the trademark Laminar by Dynachem Corporation of California. These materials polymerize when exposed to ultraviolet radiation and they may be developed in a suitable solution where the unpolyrnerized material is removed from the metal surfaces. The polymerized material which remains may be used as a resist to a metal etching solution or to a metal plating bath where an etch resistant metal is plated on the exposed metal surfaces.

Referring now to FIGS. and 6 there is shown an apparatus for exposing the upper and lower radiant energy sensitive surfaces of the strip 20a to radiant energy through masks. The upper surface of the strip 200 is exposed to radiant energy from a source 24 through masks 86-86 mounted on carriages 48-48 rolling around a first arrangement of outwardly facing circular tracks 57-60 and inwardly facing circular tracks 81 and 82. The lower surface of the strip 20a is exposed to radiant energy from a source 25 through masks 125-125 mounted on carriages 117-117 rolling around a second arrangement of outwardly facing circular tracks 126-129 and inwardly facing circular tracks 134 and 135.

The supporting framework for the tracks 57-60, 81, 82, 126-129, 134 and 135 is illustrated in FIG. 6. The tracks 59 and 81 are mounted on an annular support 63, the track 57 is mounted on an annular support 61, the tracks 60 and 82 are mounted on an annular support 64, the track 58 is mounted on an annular support 62, the tracks 128 and 134 are mounted on an annular support 132, the track 126 is mounted on an annula: support 130, the tracks 129 and 135 are mounted on an annular support 133, and the track 127 is mounted on an annular support 131. The annular supports 61, 63, 130 and 132 are mounted on plates 67 and 68 which are supported above the floor on posts 70, 71 and 72. Similarly, the annular supports 62, 64, 131 and 133 are mounted on plates 65 and 66 which are supported above the floor by three posts similar to the posts 70, 71 and 72. The plates 65, 66, 67 and 68 are all connected together by cross members 73-73 and 74-74. Additionally, the framework has an upper plate 124, a lower plate 111 and side plates 211-214 mounted on the posts (-72, etc.), and the plates 65-68 for supporting other parts of the apparatus.

The details of a carriage 48 are shown in FIG. 7. The carriage 48 has a frame 49 with wheels 50 and 51 rotatably mounted thereon for rolling along the respective outwardly facing tracks 57 and 58 (FIG. 6). Arms 52 and 53 extending from the frame 49 have respective wheels 54 and 55 mounted thereon for rolling along the outwardly facing tracks 59 and 60. Arms 75 and 76 are pivotally mounted at first ends of on the arms 52 and 53 with springs 77 and 78 urging the arms 75 and 76 toward the arms 52 and 53. Wheels 79 and 80 rotatably mounted on second ends of the arms 75 and 76 roll along the inwardly facing tracks 81 and 82. The springs 77 and 78 provide sufficient bias to hold the carriage 48 on the tracks 57-60. A pair of arms 84 and 85 extend rearwardly to support the mask 86 which is attached to the arms 84 and 85 by threaded bolts 87 and 88 and pins 89 and 90. The bolts 87 and 88 have heads in recesses 91 and 92 of the mask 86, shown in FIG. 8, to loosely secure the mask 86 to the arms 84 and 85. Shank portions of the bolts 87 and 88 extend through oblong holes 93 and 94 in the mask while the pins 89 and extend into holes 95 and 96 formed through the masks 86. The holes 93-96 are made sufficiently larger than the shanks of the bolts 87 and 88 and the pins 89 and 90 so that the mask 86 may move in a horizontal plane relative to the frame 49 within predetermined limits.

As shown in FIG. 8, the mask 86 has a plurality of pins 98- 98 for cooperating with the registration holes 32-32 that have been punched in the strip 20 as shown in FIG. 3. As previously mentioned, the apparatus for forming the holes shown in FIG. 2 cannot accurately align the holes in succeeding sections of the strip 20. The mask 86 is designed to have dimensions corresponding to a section 31a, 31b or 310 of the strip 20 and the freedom of movement of each carriage relative to the other carriages and the freedom of movement of each mask relative to its carriage assures that each mask is accurately aligned with the holes in a section of the strip even though adjoining sections may be separated by different distances and even though the holes formed in a section are not aligned with the adjacent sections.

Referring back to FIG. 7, arms 99 and 100 extend forward and slightly downward from the frame 49. The arms 99 and 100 have respective adjustable bolts 101 and 102 which abut with the back face of the arms 84 and 85 of the preceding adjacent carriage to prevent damage to the masks as the carriages roll over the uppermost portion of the tracks 57-60. Rollers 103 and 104 on the respective arms 99 and 100 support the rear end of the mask 86 of the preceding adjacent carriage.

Referring back to FIGS. 5 and 6, the carriages 117-117 and masks -125 are similar to the carriages 48-48 and masks 86-86. The carriages 48-48 move in a counterclockwise direction while the carriages 117-117 move in a clockwise direction. The wheels and arms on the carriages [17-117 are reversed so that the wheels on the tracks 126 and 127 are the leading wheels, the same as the wheels 50 and 51 on the tracks 57 and 58 are the leading wheels. The tracks 134 and are eccentric with the tracks 128 and 129. The springs biasing the arms upon which the wheels roll on tracks 128 and 129 are sufficiently strong to move the carriages against the force of gravity toward the point where the tracks 134 and 135 are closest to the tracks 128 and 129. This moves the carriages 117-117 into position to receive the strip 20a from the first arrangement of carriages 48-48.

Referring to FIGS. 5 and 6, the strip 200 passes over a rocking roller 47 and is forced by a driven flexible belt 105 moving on rollers 106-109 with the rollers 106, 107 and 109 rotatably mounted on the plates 21 1 and 212 to force the strip 20a against the masks 86-86 on the carriages 48-48. One end of the roller 108 is rotatably mounted on one end of an arm 110 which is pivotally mounted at a second end on the bottom plate 111. A piston rod 112 and an air cylinder 113 connected between the bottom plate 111 and the second end of the arm 110 pivots the am 110 to tighten or loosen the belt 105. A similar arm, piston rod and air cylinder arrangement (not shown) simultaneously operated with the air cylinder 113 supports the other end of the roller 108. The roller 109 is driven as hereinafter described.

Referring to FIG. 10, the belt 105 has an inner layer 115 which is a conventional corded belting material. The outer surface of the belting material 115 is covered with a sponge or soft resilient rubber-like material 116 which is formed into a waffle grid structure. The soft resilient material 116 presses the strip 200 firmly and evenly against the surface of the mask 86.

Referring back to FIG. 5, the strip 20a is forced by a driven belt 118 against the masks 125 on the carriages 117. The belt 118 is similar to the belt 105 and is mounted on rollers 119-122 with the rollers 119, 120 and 122 rotatably mounted on the plates 213 and 214. One end of the roller 121 is mounted on an arm 123 pivoted on the upper plate 124 by an air cylinder 143 to select the tension on the belt 118. A similar arrangement (not shown) of an arm, piston rod and air cylinder supports the other end of the roller.

Referring to FIG. 8, there is shown one method of placing a pattern on the masks 86. The mask 86 has a plate 140 which is made of a glass or plastic which is transparent to the radiant energy used to expose the strip 20a. The registration pins 98- 98 are embedded in the plate 140. An overlay 141, such as a photographic negative or the like, is placed over the plate 140 on the registration pins 98-98. The overlay 141 in FIG. 8 has an opaque background with the desired circuits transparent. As shown in FIG. 9, an alternate overlay 142 has a circuit pattern defined by an opaque image with the surrounding area transparent. The overlay 141 may be used in a process wherein the developed resist is used as a resist to the metal etching solution whereas the overlay 142 may be used in a process where an etch resistant alloy is plated on the hated metal surfaces in the developed resist pattern.

Referring to FIG. 11 there is shown a motor 150 for driving a chain sprocket 151 upon which chains 152-154 run. The chain 152 passes over a sprocket 155 which is connected by a clutch 156 to the roller 109, (FIGS. 5 and 6) and a sprocket 157 which is connected by a clutch 158 to the roller 119 (FIGS. 5 and 6). The chain 153 passes over a sprocket 159 connected by a clutch 160 to the supply reel 46 (FIG. 5). Similarly, the chain 154 passes'over a sprocket 161 connected by a clutch 162 to the take-up reel 163 (FIG. 5).

Referring to FIG. there is shown an apparatus for controlling the slack of the strip 200 between the first arrangement of carriages 48-48, and the second arrangement of carriages 117-117. The apparatus has a pair of shafts 164 and 165 which are rotatably mounted in the framework of the machine. Members 166 and 167 mounted on the ends of shafts 164 and 165 have a pair of bars 168 and 169 which support respective guide members 170-170 and 171-171 thereon. As shown in FIG. 5, the strip a loops between the guides 170-170 and 171-171 such that when there is too much slack in the strip 20a the bars 164 and 165 are rotated clockwise; and if there is not enough slack in the strip 200, the bars 164 and 165 are rotated counterclockwise. An arm 172 mounted on the shaft 165 extends between two microswitches 173 and 174 such that clockwise rotation of shaft 165 actuates switch 173 and counterclockwise rotation of shaft 165 actuates switch 174. A weight 175 mounted on the shaft 164 normally maintains the arm 172 in a neutral position between the microswitches 173 and 174. When there is too much slack in the strip 20, the arm 172 engages the microswitch 173 to operate the clutch 156 (FIG. 11) to disconnect the drive to the roller 109 and belt (FIG. 5) until the belt 118 takes up the slack to release the arm 172 from engagement from the microswitch 173. Similarly, if there is insufficient slack in the strip 20, the microswitch 174 is actuated to operate the clutch 158 to disconnect the drive to the roller 119 and belt 118 until the belt 105 again supplies additional slack,

Referring to FIG. 5 there is shown a proximity switch 176 beneath a loop extending from the supply roll 46. The proximity switch operates the clutch (FIG. 11) to maintain a predetermined amount of slack in the strip 200. Similarly, a proximity switch 177 beneath a loop in the strip 200 next to a take-up reel 163 operates the clutch 162 (FIG. 11) to maintain a predetermined slack in the strip 20a. The proximity switches 176 and 177 are a conventional design.

Referring to FIG. 13 there is shown the support for the rocking roller 47. The roller 47 has a pair of ball joints 178 and 179 which are mounted on a pair of arms 180 and 181 pivotally connected to the plates 65-68 of the apparatus shown in FIG. 6. An arm 182 extending from the plate 65 has an air cylinder 183 pivotally mounted thereon with a piston rod 184 pivotally connected to the arm 180. An oscillating air supply is connected to the air cylinder 183 to oscillate the roller 47 from side to side. The motion of the roller 47 insures that the holes 32 on the strip 200 register with the pins 98 on the masks 86.

Referring to FIG. 12 there is shown a lamp housing as sembly for supplying a beam of radiant energy to expose the top surface of the strip 20a. The assembly has a member 186 mounted on the cross members 73-73 (FIG. 6) with a screw 187 threaded through the member 186. Bars 188 and 189 are slidable in suitable grooves in the member 186. The screw 187 is supported against longitudinal movement for rotation by a cross member 190 extending between the bars 188 and 189 and a suitable bearing 198 on a lamp enclosure I92 mounted on the lower ends of the bars 188 and 189. A motor 191 mounted on the member 190 is utilized to drive the screw 187 to move the bars 188 and 189 upward and downward relative to the member 186. The lamp enclosure 192 contains a suitable ultraviolet lamp, a reflector, a collimator, a cooling fan, and such other facilities necessary for the production of the proper intensity of radiant energy necessary to expose the strip 20a. Arms 193 and 194 are pivotally mounted on the bars 188 and 189 and support a shutter 195 which may be moved by an air cylinder 196 and a piston rod 197 into or away from the face of the lamp enclosure 192. Thus, the ultraviolet lamp source in the enclosure 192 may be closed off to prevent unwanted exposure of the strip 20a and to eliminate hazardous conditions to an operator. The enclosure 192 is selectively moved toward or away from the strip 200 by the motor 191 to obtain the optimum intensity of light exposing the light sensitive material strip 20a. A similar lamp housing assembly (not shown) is mounted on the cross members 74-74 (FIG. 6) with the lamp enclosure face upward to expose the bottom surface of the strip 200.

Referring to FIG. 14, there is shown a belt press assembly having a pair of side members 199 and 200 which are supported in the framework for engaging the belt 105 to provide additional pressure on the belt forcing the upper surface of the strip 20a against the masks 86-86. The belt press member has a plurality of rollers 201-203 mounted on respective Pairs of arms 204-206 which are pivoted on the members 199 and 200. Springs 207-209 are attached to bars 210-212 mounted on the arms 202-204 and the members 199 and 200 to urge the rollers 201-203 upward against the belt as shown in FIG. 5. A similar belt press assembly (not shown) is provided for pressing the belt 1 l8 and lower surface of the strip 20a against the masks 125-125.

After the resist layers 40b and 41b have been selectively exposed to radiant energy, the resist is developed and the circuits are formed in a conventional manner such as by etching, or by plating an etch resistant metal or alloy and then etching. Electrical connections may be made through selected holes between circuit patterns on opposite sides of the film 2] by conventional techniques such as electroless plating of copper followed by electrolytic plating of copper. The forming of connections through the holes may be made at any time or step after the holes have been punched. Forming of additional resist coatings may be necessary for the forming of connections through the holes, or the resist layers 40b and 41b may be used prior to forming and etching the circuit patterns.

It is to be understood that the above-described embodiments are simply illustrative of the principles of the invention and that many other embodiments may be devised without departing from the scope and spirit of the invention.

What is claimed is:

1. An apparatus for exposing a radiant energy sensitive strip of material, comprising:

a source for projecting a beam of radiant energy;

a track running past the projected beam of radiant energy;

a plurality of individual carriages movable along the track,

each carriage having a mask thereon; and

means for moving the strip adjacent to the carriages and for moving each carriage in registration with a predetermined section of the strip through the beam of radiant energy with the masks between the source and the strip.

2. An apparatus as defined in claim I, wherein there are registration holes formed in the strip and each mask has a plurality of registration pins mounted therein for holding the strip in registration with the mask.

3. An apparatus as defined in claim 1, wherein the track is enclosed and the moving means is adapted to move the strip and carriages continuously through the beam of radiant ener- 8y- 4. An apparatus as defined in claim 2, wherein the holes are made by punching successive sections of the strip and each mask corresponds to a section so that each mask may be accurately aligned by the registration pins with a section of the strip.

5. An apparatus as defined in claim 2, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.

6. An apparatus as defined in claim 3, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.

7. An apparatus as defined in claim 4, wherein each mask is mounted free to move within predetermined limits relative to each respective carriage so that each mask may be accurately aligned by the registration pins with a section of the strip.

8. An apparatus for exposing a radiant energy sensitive strip of material wherein the strip has a plurality of holes formed in successive sections thereof, comprising:

a source for projecting a beam of radiant energy;

an enclosed track;

a plurality of carriages movable along along the track;

a plurality of masks, one for each carriage, each mask having a plurality of pins for registering with the plurality of holes formed in each section of the strip;

means for mounting each mask on a carriage with the mask free to move within predetermined limits relative to the carriage so that each mask may be accurately aligned by the registration pins with a section of the strip; and

means for moving the strip into engagement and registration with successive masks and for moving the carriages and strip through the beam of radiant energy with the masks between the radiant energy source and the strip.

9. An apparatus as defined in claim 8, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.

H]. An apparatus as defined in claim 8, wherein the mask comprises:

a substantially transparent rigid plate having the registration pins mounted therein; and

an overlay with registration holes therein secured to the plate, said overlay being transparent with opaque areas defining a pattern.

ll. An apparatus as defined in claim 8, wherein the track is circular.

12. An apparatus as defined in claim 8, wherein there are a plurality of tracks supported by a frame in a plurality of parallel planes for guiding the plurality of carriages.

1 F II i i 

1. An apparatus for exposing a radiant energy sensitive strip of material, comprising: a source for projecting a beam of radiant energy; a track Running past the projected beam of radiant energy; a plurality of individual carriages movable along the track, each carriage having a mask thereon; and means for moving the strip adjacent to the carriages and for moving each carriage in registration with a predetermined section of the strip through the beam of radiant energy with the masks between the source and the strip.
 2. An apparatus as defined in claim 1, wherein there are registration holes formed in the strip and each mask has a plurality of registration pins mounted therein for holding the strip in registration with the mask.
 3. An apparatus as defined in claim 1, wherein the track is enclosed and the moving means is adapted to move the strip and carriages continuously through the beam of radiant energy.
 4. An apparatus as defined in claim 2, wherein the holes are made by punching successive sections of the strip and each mask corresponds to a section so that each mask may be accurately aligned by the registration pins with a section of the strip.
 5. An apparatus as defined in claim 2, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.
 6. An apparatus as defined in claim 3, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.
 7. An apparatus as defined in claim 4, wherein each mask is mounted free to move within predetermined limits relative to each respective carriage so that each mask may be accurately aligned by the registration pins with a section of the strip.
 8. An apparatus for exposing a radiant energy sensitive strip of material wherein the strip has a plurality of holes formed in successive sections thereof, comprising: a source for projecting a beam of radiant energy; an enclosed track; a plurality of carriages movable along along the track; a plurality of masks, one for each carriage, each mask having a plurality of pins for registering with the plurality of holes formed in each section of the strip; means for mounting each mask on a carriage with the mask free to move within predetermined limits relative to the carriage so that each mask may be accurately aligned by the registration pins with a section of the strip; and means for moving the strip into engagement and registration with successive masks and for moving the carriages and strip through the beam of radiant energy with the masks between the radiant energy source and the strip.
 9. An apparatus as defined in claim 8, wherein the moving means includes a movable continuous resilient belt which urges the strip against the carriages as they pass through the beam of radiant energy.
 10. An apparatus as defined in claim 8, wherein the mask comprises: a substantially transparent rigid plate having the registration pins mounted therein; and an overlay with registration holes therein secured to the plate, said overlay being transparent with opaque areas defining a pattern.
 11. An apparatus as defined in claim 8, wherein the track is circular.
 12. An apparatus as defined in claim 8, wherein there are a plurality of tracks supported by a frame in a plurality of parallel planes for guiding the plurality of carriages. 